Every vulnerable Senate Democrat up for re-election in 2014 voted with President Barack Obama at least 90 percent of the time in 2013, according to CQ Roll Call's latest vote studies , released Monday.

Arkansas Democrat Mark Pryor broke with the president most often, opposing him in 10 percent of all 2013 votes where the administration stated a preferred outcome. Sens. Mark Begich, D-Alaska, Mary Landrieu, D-La. and Kay Hagan, D-N.C., voted for Obama's position 97, 97, and 96 percent of the time, respectively. Of those four, only Begich serves with a Republican who has bucked the GOP to back Obama with any frequency. (See our Jan. 21 story .)

On the flip side, Republican senators who are wary of primary challengers from the right opposed Obama so often that the president's support from GOP senators in 2013 — 40 percent — was the lowest of his five years in office. Senate Minority Leader Mitch McConnell, R-Ky., opposed Obama 67 percent of the time. Sens. Pat Roberts, R-Kan., Thad Cochran, R-Miss., Lindsey Graham, R-S.C., and John Cornyn, R-Texas, opposed the Obama position on 66, 50, 48 and 66 percent of votes respectively.

The degree to which Democrats were willing to vote with Obama — and Republicans were determined to oppose him — translated into very different rates of success for the president in the two chambers.
After prevailing on almost 97 percent of the votes in the two chambers on which he took a position in 2009 and almost 86 percent in 2010, when Democrats controlled both House and Senate, Obama’s success rate fell sharply. He won barely more than half of the time during the past three years. Not surprisingly, he remained highly successful in the Democratic Senate, while the Republican House granted him few victories.
Obama was victorious on 85 percent of the 108 Senate votes last year on which he took a position, the majority of which involved nominations to executive branch posts and judgeships. That success rate was a bit higher than in the election year of 2012 but in line with the rates of the three preceding years.
In the House, however, he won just 21 percent of the time when he signalled his stance, roughly the same as in 2012 but down from his 32 percent success rate in 2011. President Bill Clinton had higher success scores during all six years in which he worked with a Republican-led House.

The Obama support/opposition matrix can be viewed in a neat graphic here ($).